t7l 



West Texas and Southeast New Mexico. 335 



along which the El Paso and Southwestern Railroad extends 

 between El Paso and Alamogordo, a zone of faulting marks 

 the western foot of the Sacramento Mountains. Ped beds, in 

 fault contact with limestones of Mississippian age, form the 

 local base of the upper Carboniferous section in this vicinity, 

 These red beds constitute the western escarpment of the Sacra- 

 mento Mountains, and are at least 2,000 feet thick, the section 

 being obscured by faulting. They consist of a variegated 

 group of prevailing red sandstone and shale, minor beds of 

 buff sandstone and drab shale, and lenses of gray limestone. 

 The red beds are overlain by a great mass of limestone 

 and subordinate gray sandstone having a minimum thick- 

 ness of 3,000 feet. These upper strata form the eastern 

 slope of the Sacramento Mountains, which is thirty miles 

 long, the strata dipping low to the east at an angle slightly 

 greater than the inclination of the surface. Numerous fossils 

 have been collected at various horizons from the lime- 

 stone lenses in the red beds and from the overlying strata. 

 Dr. Girty states they are all unmistakably Pennsylvanian and 

 correlates them with the fauna of the Hueco formation. This 

 correlation is strengthened by the partial tracing of the beds 

 from the southeastern base of the Sacramento Mountains into 

 limestones in the upper part of the Hueco formation exposed 

 in Texas east of the Cornudas Mountains ; and by the recent 

 discovery of red beds in a well north of Sierra Blanca (p. 329). 

 This latter occurrence appears to represent the southern wedg- 

 ing out of the mass of red beds exposed in the escarpment of the 

 Sacramento Mountains. 



The description of this section may here be interrupted to 

 revert to the rocks of the Guadalupe Mountains, the northern 

 end of which coalesces with the eastern base of the Sacra- 

 mento Mountains. It will be recalled that the rocks of the 

 Guadalupe Mountains at their southern termination in Texas, 

 near the New Mexico boundary, consist of about 4,000 feet of 

 sandstone and limestone which have been separated into the 

 Delaware Mountain formation and the Capitan limestone, the 

 relation of which to the Hueco limestone, in Texas, is con- 

 cealed by the Quaternary deposits of the Salt Flat bolson. In 

 the New Mexico portion of the Guadalupe Mountains a more 

 complete section is exposed than in Texas, and there the Capi- 

 tan limestone is overlain by a few thousand feet of limestone 

 and sandstone as stated above (p. 331). Throughout this entire 

 region, the general dip is eastward at a low angle. The strati- 

 graphy is varied, and both the Delaware Mountain formation 

 and the Capitan limestone lose their individuality when traced 

 far along the strike. The massive Capitan limestone, for 



